Postkeynesian theorists emphasise the fact that Keynes’ economic process is recursive rather than Walrasian. Such recursiveness proceeds from an exogenous and "conventional" monetary interest rate to the expected marginal efficiency of capital, while money supply is endogenous. In spite of the crucial role attributed to the banking system in the transmission of interest rate impulses, postkeynesians make little room to for the way in which banks fix their interest rates, as well as to the role of credit conditions. This paper contains a brief description of some micro-foundations of the postkeynesian theory, mainly based on the role played by asymmetric information. JEL Classification: E120, E400